I guess you best ask the tag standardisation committee to have this added as a tag to a track.Problem likely is that Cue is a pretty personal preference. And even more complicated it may vary depending on the situation. As e.g. intro's are not wanted in mash ups.

The Cue point (and all markers/loops) are set at timestamp (like 1/1,000,000 of a second accuracy).

The algorithm Cross uses for the Cue point thries to set the best point somewhere at the beginning that makes smooth transitions possible. In the past a lot of parameters were available and still didn't satisfy everyone let alone every track. So it evolved in a smart algorithm without parameters leaving the tweaking to the user.

Why couldn't CrossDJ just store the cue info within the media file (.mp3 .mp4) like Serato does? Although Serato is secretive about their Cue writing algorithm, it is known by partners like MixedInKey and so can be reverse engineered. Heck I think even vDJ can read Serato Cue tags.

In my mind there is no hope for CrossDj to appeal to pro/advanced users unless this situation with the metadata can be better managed.

In its current state its just a fancy mp3 player. I really like this piece of kit and just wish the devs would DO SOMETHING.